Copyright © 2014 Future Technology Devices International Limited

23

Document No.: FT_000646

FT120 USB DEVICE CONTROLLER WITH PARALLEL BUS IC

Datasheet Version 1.2

Clearance No.: FTDI#

291

6.4.1 Read Current Frame Number

Command

: F5h

Data

: Read One or Two Bytes

Bit

Symbol

Reset

Description

7-0

Frame Number LSB

00h

Frame number for last received SOF, byte 1 (least

significant byte)

Table 6-14 Frame Number LSB Register

Bit

Symbol

Reset

Description

2-0

Frame Number MSB

0b’000

Frame number for last received SOF, byte 2 (Most

significant byte)

7-3

Reserved

0b’00000

Reserved

Table 6-15 Frame Number MSB Register

6.4.2 Send Resume

Command

: F6h

Data

: None

To perform remote-wakeup when suspended, the MCU needs to issue Send Resume command. The

FT120 will send an upstream resume signal for a period of 10 ms. If the clock is not running during

suspend, the MCU needs to wakeup FT120 by drive SUSPEND pin to LOW, followed by Send Resume

command.